Safety pilot



Aug. 15, 1944. Afp. LlvAR SAFETY PILOT Filed July 2o, 1942 INVENTOR Mm n L i Patented Aug. 15, 1944 SAFETY PILOT Allen P. Livar, Dayton, Ohio, assignor to Chrysler Corporation, Detroit, Mich., a corporation of Delaware Application July 20, 1942, Serial No. 451,611

. 1 Claim.

My invention relates to pilot devices for fuel burning appliances, having particular reference to gas burning appliances although the inven- (Cl. 15S-117.1)

through a modification of a portion of the apswitch operator .to replace the commonly used separate units, the entire combination of my invention being capable of fabrication at a total cost far less than the cost of fabrication of separate pilot devices and safety switch operator now known to me.

A further object of the present invention is to provide a combination pilot burner and safety switch operator which may be easily assembled with a heating appliance and quickly removed for inspection. y

A further object of the present invention is I to provide a combination pilot burner and safety switch operator containing only one moving element, whereby fatigue failures and mechanical failures are substantially eliminated.

A furthery object of the present invention is to provide a pilot burner and safety switch operator, wherein the cooling action-0f the gaseous fuel flowing through the pilot burner upon exl tinguishment of the pilot flame causes rapid reaction of the safety switch operator to close the fuelvalve or other device controlled by the safety switch. I l

`These and `other objects and advantages of the present invention may be more fully under` stood by reference to the accompanying drawing paratus. I

The drawing illustrates a portion of thewall I0 of a fuel burning appliance having an open-A ing II therethrough through which the portion of the assembly to be enclosed within the casing may be inserted. The assembly comprises a pilot burner I2 mounted in a holder I3 adapted to be attached to the end of a fuel supply tube I4 projecting from a mounting block I5 fastened to the wall IIJ by a bolt I6. The tube I4 communicates with a threaded opening I1 adapted to receive the end of a pipe leading to the source of fuelsupply, and communicates at its other end with the interior of the4 pilot burner through a passage I8 drilled through the holder I3 at a diagonal to the axis of the tube I4 so that the pilot burner I2 may extend horizontally above the axis of the tube I4. An opening 20 is drilled through .the holder I3 axially of the tube I4 and communicates with a threaded opening 2| extending into the opposite side of the holder I3 from that side to which the tube I4 is fastened. A capsule 22, having its open end threaded, is screwed into theopening 2I and sealed thereto as by means of tinning the threads or applying a fillet'23 .of solder or the like. A length of fine tubing 24 having an internal diameter of the order of several thousandths of an inch Vand preferably having a very thin wall extends through the opening 20 and has its end sealed to the inner end of the opening 2I as by means of a llet 25 of solder or the like. The free end of the tubing 24 extends through an opening 26 metallic bellows 29 communicating with the bore of the tubing 24 and mounted in the bore 21. The end cap of bellows 29 carries an insulating plate 30 upon which is mounted a switch plate and following specification wherein a preferred embodiment of the present trated and-described.

In the drawing,

Fig. 1 is a vertica1, longitudinal section through a device of the present invention;

Fig. 2 is a vertical cross-section through a portion of a preferred form of pilot burner taken substantially along line 2-2 of Fig. 1;

Fig. 3 is a longitudinal section taken through the preferred pilot burner; and i Fig. 4 is a vertical, longitudinal section invention is illus- 3|. "The plate 3l Ais adapted to strike contact points 32 `and 33 preferably Athreadedl into an insulating, cap 34 for adjustable movement lengthwise of the bore 21. The contacts 32 and 33 are fastened t wires 35 and 36, respectively, which lead tothe fuel valve or other mechanism intended to be operated by the safety switch.

A preferred form of pilot burner is illustrated, but it should be evident to those skilled in the art that other formsmay be utilized. The pilot burner comprises a body member 40 having aV fuel injection orifice 4I surrounded by air inspirating ports 42. The body 40 carries a short length of tubing 43 upon which is mounted the tip member u which is provided with a vertical slot 45 Joining a plurality of ports 48, at least one of which is preferably dlrectedso as to project a tongue of iiame against a portion oi.' .the capsule 22.

The capsulezz, tubing 2l, and bellows 29 provide a sealed enclosurewithin which is sealed an expansible iluid adapted upon being heated to extend the bellows 29 so as to cause the switch plate 9| to bridge the gap between contacts I2 and 93, and upon cooling to permit contraction of the bellows so as to open the switch circuit. Preferably the capsule 22 is formed of heat resisting steel and the interior space is lled with an inert gas such as nitrogen or the like. In order to facilitate manufacture, the interior surface `of the capsule, particularly that portion adapted to'be heated to a high degree by the pilot llame impinging thereon, is treated to be rust resistant, such as by Parkerizing, or any similar process designed to provide a coating of metallic salts on the surface of the steel so as to prevent oxidation thereof. This eliminates thev necessity for using an inert gas and the interior space may be lled with ordinary air at atmospheric pressure (or at higher or lower pressures if desired) or with air and a quantity of water to form steam. If facilities are available the interior space may be lled with absolutely dry air without treating the interior surface of the capsule since the presence oi' moisture is absolutely necessary for the formation of rust. Any expansible gas or liquid may be used provided that the` quantity of uid sea1ed.within the interior space is not subject to reduction. such as by oxidation or other chemical reactions, or by absorption of the iluid into the metal walls.

A modiilcation of the invention is disclosed in Fig. 4 wherein it is seen that the bore 21 in the mounting block I5 is threaded to receive a plug 50 of insulating material, such as hard rubber or the'like. within which thecontacts 32 and 33 are mounted. 'Ihe plug 50 is adapted to be adjusted longitudinally of the bore 21 to compress to a greater or lesser extent a spring 5I bearing against the end of the plug and the end of the bellows 29. Equal adjustment of the two contacts may be accomplished by turning the plug 50, and alteration'of the range of operation of the switch device is likewise accomplished by changing the degree of compression of the spring 5|. A further advantage is that positive action of the bellows 29 in a collapsing direction is further assured.

It is to be noted that the tube 2l is enclosed within the tube I4 so that danger of burning or overheating the walls of the tubing is eliminated, and also so that the principal length of the tubing will be constantly surrounded by a stream of gas at a constantly cool temperature so as to eliminate variations in reaction time which might be caused by heating the walls of the tubing. It is also to be noted that the cooling action of the gas surrounding the tubing 24 and of the jet of gas projected against the capsule 22 when the pilot flame is extinguished is such as to hasten vcollapsing of the bellows 29 and opening of the safety switch circuit.-

It should be apparent to those skilled in the art that modifications in arrangement and detail may be readily achieved. All such modiilcations as come within the scope of the following claim are to be considered a part of my invention.

I claim:

A safety pilot assembly for a fuel burningl appliance comprising a holder formed with an aperture, a pilot burner mounted in said aperture and extending outwardly therefrom, a thermostatic element mounted in the holder in spaced relation to the pilot burner and adapted to be heated by llames generated in the burner, a fuel supply tube having one end connected to the holder, said holder being provided with a duct communicating with both said pilot burner and said supply tube, a. length of ilne tubing positioned within the supply tube and communicating at one end with the interior of the thermostatic element, a lblock member spaced from said holder and formed with one aperture receiving the other end of the supply tube and with a second aperture for receiving a main supply pipe, and an extensible pressure responsive element positioned in the block and connected with the opposite end of the length ot ne tubing.

ALLEN P. LIVAR. 

